Pigmented outside side striper

ABSTRACT

A device for side striping cans which uses a single belt having slots of can length along its middle. The slot gives good edge resolution to each can and avoids leakage of the side stripe material into the interior of the can.

United States Patent Winkless [451 July 11, 1972 [54] PIGMENTED OUTSIDE SIDE STRIPER [21] Appl.No.: 89,922

Related 1.1.8. Application Data [63] Continuation-impart of Ser. No. 767,582, Oct. 3,

2,695,592 11/1954 Szczepanski.,,..........,.............l18/301 3,326,182 6/1967 Kiyoshi lnoue... ....118/629 3,205,855 9/1965 Ault ....1l8/301 2,815,734 12/1957 Carlson ....1 18/630 2,505,063 4/1950 Palermo..... ....118/301 2,088,542 7/1937 Westin ....1 18/301 3,336,905 8/1967 Lehmann ..1 18/637 Primary ExaminerMervin Stein Assistant Examiner-Leo Millstein Auomey--Americus Mitchell, Joseph E. Kerwin and William A device for side striping cans which uses a single belt having slots of can length along its middle. The slot gives good edge resolution to each can and avoids leakage of the side stripe 1968, abandoned. A. Dittmann [52] U.S.Cl ..ll8/2, 118/501, 118/301, 57 BSTR CT 118/326, 118/630 [51] Int. Cl. ..B05c 11/00 [58] FleldolSeamh ..118/50,50.l,301,62l,623,

material into the interior of the can.

[56] Relerences Cited 20 Claims, 10 Drawing Figures UNITED STATES PATENTS 2,996,040 8/1961 Bofinger ..1 18/301 16 17 17 2 1 163@010Q9613QfilnfiflfiabfififibflfiQfiifif VACUUM 33 V SOURCE 3 POWDER I 35 DISPENSER 1/ so la '12 P'A'TENTEDJUL 1 1 1972 SHEET 10F 3 ROBERT A. WINKLESS PKTENTEDJUL 11 m2 3,675.61?

sum 3 or a VACUUM SOURCE INVENTOR ROBERT A. WINKLESS BY mm ATTY.

PIGMENTED OUTSIDE SIDE STRIPER This application is a continuation-in-part of my application titled Pigmented Outside Side Striper, by Robert A. Winkless, Ser. No. 767,582 and assigned to Continental Can Company, Inc., assignor of this invention, which is now abandoned.

My invention relates to a mechanism for coating the side seams of cans, and more particularly, to a mechanism for feeding the cans in spaced relationship along an assembly line while providing for a uniform application of side striping material to the can seam.

In the manufacture of cans, the blank stock is ordinarily coated while the material is flat. Since the cans are usually welded after this operation, the edges of the blank stock are cleaned so that the welding process forms an impervious joint. After welding, it is necessary to apply side striping or coating to the side seam of the can to protect the seam from corrosion and for esthetic appeal. This operation is performed many times a minute. Cans are placed onto the conveyor chain and after welding, the cans enter a striper unit and after striping are removed from the chain. The handling of cans is facilitated if they are spaced from each other by some distance.

The edges of can bodies may be fastened to each other by any means. The side striping is applied to protect the can seam where necessary against corrosion and for esthetic appeal.

It is an object of this invention to provide a device for side striping cans which are spaced apart a definite distance without allowing any of the striping material to pass into the can.

It is another object of this invention to provide an apparatus for side striping without spraying objectionable pigmented matter into the interior of the can.

It is a further object of this invention to provide a feed line wherein the cans are striped by a fluidized powder to cover sharp edges.

It is a final object of this invention to provide a high speed coating device for cans.

Other objects and advantages of the present apparatus become apparent in the following discussion of the drawing wherein:

FIG. I is a side view of a moving belt striper.

FIG. 2 is an end view of the can mounted on a belt.

FIG. 3 shows the top view of a can mounted on the belt.

FIG. 4 shows a longitudinal cross-section of a welded can with uneven application of coating material.

FIG. 5 shows a cross-section of a welded can with a stripe applied.

FIG. 6 shows a side view of another embodiment of my moving belt striper.

FIG. 7 shows a configuration of the exit nozzle.

FIG. 8 shows a special configuration of the exit nozzle.

FIG. 9 shows a schematic of the high-low vacuum system of FIG. 6.

FIG. II] shows an end view of a can mounted on an improved belt.

In brief, my invention is a moving belt striper in which the center of the endless belt has longitudinal slots spaced along its length. The belt is disposed over rollers and the can is placed in one of the slots with the can seam down. The endless belt passes over a nozzle from which a pigmented coating powder flows. The powder coats only the outside seam with a band of uniform width, and no powder passes into the interior of the can.

The belt 1 of this invention is supported by three pulleys 2 in FIG. 1. The power drives of the preceding welding operation and of the striping operation are synchronized and in phase so that each can 3 is introduced onto the belt and falls exactly in the slot 4 of the belt (FIGS. 2 and 3) with the seam down, and each can is spaced from each other can a distance equal to the bridge or covered space between the cans. The can seam is hot and may heat the edges of the slot 4. An electrically neutral material which is electrically neutral or of high resistivity or an insulator which does not wet and melts at a temperature higher than the wetting point of the pigmented or non pigmented powder is used for the belt. The belt may be made, for example, of fiberglass impregnated with teflon or nylon. By using this type of belt, any powder falling onto the belt may be readily separated from the belt at a later stage, even if the powder has fused on the belt.

The can travels from left to right and at about midpoint of its traverse, the can passes over a nozzle 6. As the can and belt slot pass over the nozzle, the coating material or striping powder 7 jets out from the nozzle and strikes against can 3. The noule is placed near to the can to avoid material loss and inclines toward the can at a small angle to avoid particles bouncing off the can. The nozzle exit is rectangular in crosssection for even distribution of coating material on the can. If shading of coating material is desired, an appropriate nozzle exit configuration is used to control the thickness of the material at different points across the stripe. The width of the nozzle is about the same width as the slot to give maximum transmission of powder to stripe the can.

The striping powder must be attracted to the can side and must adhere to the can side. This is accomplished by charging the powder electrostatically and keeping the can at ground potential. Any charging means, such as corona discharge, sparks, arcs or radiation, may be used. In the embodiment shown, the striping powder 7 is charged negatively by the corona charging pins 8 which are maintained at a sufficiently high voltage to produce corona. The highly charged pins taken in conjunction with the can body give rise to an electric field that directs the electronegatively charged particles to the can and away from the pins. This function may be effected by a charged plate if corona pins are not used. The pins may be vertical or horizontal and are in a well through which air is drawn to clean the area. The use of corona discharge gives greater stability and higher operating voltages and currents are possible than in the other mentioned means.

When the charged particle hits the hot weld area, it gives up part of its charge to the can. The powder becomes somewhat conductive as it is heated by the hot weld area. The powder charge partly flows to the can, and the remaining electrostatic charge holds the powder to the can. Since most of the charge leaks off the powder, the surface does not present a repelling charged surface to particles subsequently arriving.

The negatively charged striping powder 7 is attracted to and adheres to the can 3 which is at ground potential. The bridge elements 15 of the belt block the pigmented powder from entering the interior of the can. As no pigmented or colorless powder flows into the interior of the can, a more attractive appearance is presented than would be the case if pigmented powder were found sprayed at spots inside the can. Further, the composition of the inside and outside powders may be different and the powders may be incompatible. One powder may not stick to the other or may even react chemically with the other powder to produce a chemical compound which is not suitable for coating. For these and other reasons it is desirable to keep the inside striping powder separated from the outside striping powder. The use of bridge 15 eliminates these problems. The can proceeds to the right and passes off the conveyor to the next operation where the powder may be heat-fused to the can.

Some of the sprayed powder contacts the endless belt and adheres to the belt mask. The pigmented powder must be cleaned from the belt to avoid transmitting a smudge to subsequent cans. This powder is carried around on the belt to the belt cleaning station and is swept off by rotating low density nylon brushes inside housing 12.

Mounted to the right of the charging pins 8 is a port 9 connected to a vacuum source 10 which removes excess powder from the area of the nozzle charging pins 8. The degree of vacuum is low to avoid pulling powder from the can and to allow the charged powder to move onto the can, but the degree of vacuum is sufficient to remove excess or uncharged powder from the area. This excess powder may be conducted from the vacuum source to a dust collector.

The powdered spray material is electrostatically charged, and after being charged, proceeds in a more or less straight line toward the can body under the influence of the electric field and the pneumatic force from the nozzle stream. The material is intercepted by the edges of the belt, i.e., the powder falls onto either the can or onto the belt to provide a sharp edge for the can stripe. For sharpest definition, the belt is mounted close to the can but need not touch the can.

The top plan view of FIG. 3 shows a belt in section and a can fitted into one of the slots in the belt.

Another effect of using a segmented belt is that unevenness of coating is avoided. A belt having a slot all the way down its center allows some of the coating material to tail over its end and into the interior of the can (FIG. 4). An uneven outside coating is produced and if some specific thickness is desired, a large excess of coating material must be applied to the center so that the ends are coated to the desired thickness. When a segmented belt is used, no material tails over into the interior of the can, and an even coat is applied along the length of the stripe. Thus, if a certain thickness is desired, it can be applied evenly with considerable savings of material by using a segmented belt, compared to the amount of materal used without the segmented belt.

If a pigmented powder is placed into suspension in a liquid carrier and then applied to a weld having a sharp edge, such as shown in FIG. 5, the liquid then flows under the influence of surface tension and is either thin at the sharp edge or exposes the sharp edge. Fluidized powder applied from a rectangular nozzle exit lies evenly across the strip and coats each part of the area to about the same depth. The powder does not flow in the manner of a liquid, but coats the sharp edge as shown in FIG. 5. By using fluidized powder, a savings of pigmented material is effected.

Another embodiment of my invention shown in FIG. 6. For consistency, the same numbers are applied to FIG. 6 as are applied to like items in FIG. I. The belt 1 of FIG. 6 is supported by four pulleys 2. The power drive of the preceding welding operation drives both the chain 16 with dogs 17 and the belt 1 of the striping operation. The belt and chain are synchronized and in a phase relationship so that each can 3 is introduced onto the belt 1 at a point where it falls exactly in the slot 4 of the belt, (FIGS. 2 and 3) with the seam down. The operation of the belt, can and nozzle 6 are the same as explained in reference to FIG. 1 in preceding paragraphs.

Cleaning air passes along the length of corona pins 8 and keeps the pins free of powder particles. The tip of each corona pin must be especially clean because powder adhering to the tip may substantially prevent electrons from discharging from the tip of the pin. Further, absence of an electron field around the pin causes an abrupt voltage gradient near the pin tip thus lowering the voltage which may be applied to the pin before electrical arcing takes place. One pin or preferably a plurality of corona pins may be used for greatest efficiency. Pins are placed about one half inch apart to avoid corona overlap.

Alternatively, cleaning air may be passed across the pins and pin tips. The corona discharge is not efiectively altered by the direction of travel or the cleaning air and powder particles deposit onto the can side seam no matter which way the cleaning air is directed.

The cans 3 are moved along the belt 1 in synchronism with the belt. The cans are actually pushed along by dogs 17 attached to the overhead chain 16. As the chain wears because of long usage the synchronism between the chain and the belt drive varies slightly. For this reason a variator 18 is put in the drive of the belt. Thus, when the chain wears or for any other reason a variance is found between the chain positioning of cans on the belt as to the belt slot, the variator 18 can be adjusted to bring about a correspondence between the can body and the can slot.

The variator sprockets l9 and 20 are keyed to input shafts and output shafts of the variator respectively. The other four sprockets 21, 22, 23 and 24 are essentially idler sprockets having no power function. The idler sprockets 2i and 22 are mounted in or on a housing 25 which is slidable and is adjustable by screw 26. The adjustment is shown outside the variator. This adjustment may be made automatically in response to sensing means mounted near the belt and chain for sensing a phase difference if so desired. An endless roller chain 27 is wound around all of the sprockets as shown in variator 18. The variator operation is readily understood by assuming that input sprocket 19 is stationary while the slidable housing 25 is lowered. As the slidable housing is lowered the output sprocket 20 rotates in a counterclockwise direction and the belt 1 will move backward a small amount. This variator can be operated while the sprockets are rotating or while the sprockets are still. The sole purpose of describing the output sprocket rotation when the sprockets position is fixed is for more easy understanding of the operation. By use of this variator between the chain and belt drive, a fine adjustment is possible to allow the cans to fall exactly into the slots 4 of belt I.

The nozzle exit or orifice of the nylon tube 29 may be rectangular, or may be an elliptical exit 30 as shown in FIG. 7 or may be given a special shape exit 3] as shown in FIG. 8. In any case, the cross-sectional area of the nozzle exits 30, 3] must be very close to the cross-sectional area of the tube 29 which brings the suspended powder up to the nozzle. In this way, the velocity of the gas and suspended powder is very nearly the same throughout the extent of the tube 29 and nozzle. This is true so long as the nozzle is the same cross-sectional area as the area of the tube through which the suspended powder passes. As long as the powder velocity stays above the critical velocity, the powder has little or no tendency to adhere to the sides of the exit 30 or exit 31. Thus, there is little or no clogging and the powder comes out of the shaped nonle in the desired crosssection. The cross-section density of the powder coming out remains at about the same cross-sectional density as the powder suspension which is found in the tube. Also, the fluid density through the nozzle 6 remains above the critical transport velocity.

The transport tube 29 is made of a non-wetting material such as nylon to lessen the tendency for powder to clog in the tube. The powder transport velocity through the tube must be kept above the critical transport velocity to avoid powder adhering to the sides of the tube. It has been found that the critical transport velocity depends upon diameter of the powder, the diameter of the tube, the kind of gaseous transport material pressure and the material of the powder. The powder velocity in the production model is about 20 foot per second. Critical powder velocity is about five foot per second for a tube having an inside diameter of thousanths of an inch. A very fine powder on the order of five microns in diameter tends to adhere to the sides of the tube at any transport speed because Vander Walls forces take over for this size particle. For particles larger than this, up to and on the order of microns, the factors noted above determine the critical transport velocity and tube diameter. The diameter of the tube must be uniform throughout. 1n the event that the diameter of the tube is too great, powder deposits around on the walls of the tube and builds up into the tube thus decreasing the effective tube diameter until such time as the critical transport velocity for this powder in its mass is achieved. When the critical transport velocity of this powder is achieved, the powder stays in suspension in the gas which is used for transport purposes. Allowing this to happen might be one solution to the problem of achieving critical transport velocity. However, it has been found that if the tube is jiggled, tapped or disturbed in any way, segments of the deposited powder fall into the gaseous transport material and a slug comes out of the nozzle. This slug is quite undesirable from the standpoint of coating the side seams because of the powder loss and great variance in side seam coating. Slugs must be avoided. Avoidance of a possible slug or plug of powder is achieved by reducing tube size until the critical transport velocity for this size powder in the gaseous transport medium is achieved. In short, by selecting the appropriate tube size a critical transport velocity for a Another advantage is that by the use of a segmented belt, pigmented material is prevented from passing into the interior of the can to spoil its esthetic appearance. Further, a much thinner coat of pigmented material can be applied from end to end of the can, since all of the powder material goes onto the can without loss of powder into the can at the can end.

Another advantage of this invention is that in normal usage, no pigmented material will find its way into the interior of the cans to spoil the esthetic appeal of the can and prevent possible chemical reaction with other internal coatings.

Other advantages of my embodiment are that a powder of uniform cross-sectional density is deposited on the can, a shaped nozzle allows selective deposition of powder from the seam and a high-low vacuum system prevents unwanted deposit of powder in places other than the can seam.

Finally, a variator allows exact correspondence between the can and slot in the belt.

The foregoing is a description of an illustrative embodiment, and it is applicants intention in the appended claims to cover all forms which fall within the scope of the invention.

What is claimed is:

l. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width comprising:

can feed means for feeding spaced can bodies past an application station;

an endless belt having slots spaced in series with their longitudinal axes along the direction of motion of said belt and traveling parallel to and in synchronism and phase with said can feed means whereby said can may be placed at said slot with its side seam toward said slot;

means of projecting powdered striping material in a direction generally parallel to the direction of motion of said can feed means;

means for electrostatically charging said striping material;

and

means for charging said can to a different potential from said striping material whereby said charged striping material is attracted to said can to coat said can.

2. A can side striping device for coating the hot side seam of can bodies as set forth in claim I in which said endless belt comprises:

a thin belt made of a non-wetting, high-melting point, flexible material.

3. A can side striping device for coating the side seam of can bodies as set forth in claim 2 in which said thin belt is located very close to said can.

4. A can side striping device for coating the side seam areas of can bodies as set forth in claim 1 comprising further:

a vacuum source mounted adjacent said electrostatic charg ing means for cleaning the charging means; and

a cleaning means mounted adjacent said endless belt for wiping striping material from said belt after it has passed said vacuum source.

5. An apparatus for coating the side seam of a series of spaced cans comprising:

can feed means for feeding spaced can bodies past an application station;

a segmented endless belt disposed over rollers and having slots whose longitudinal axes extend in the direction of motion of said belt and of width and length such that a can may be placed upon said slot and the hot side seam fits snugly into said slot,

means for projecting striping material in a direction generally parallel to the direction of motion of said can feed means, and into said slot area;

means for electrically charging said striping material; and

means for grounding said can whereby said striping material is attracted to said can.

6. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which said projecting means comprises:

a nozzle having a shaped exit orifice for control of the amount of striping material deposited at points on said can.

7. An apparatus for coating the side seam of a series of cans as set forth in claim 6 in which:

said shaped exit orifice has a cross-section with the outline of a rectangle whereby said powdered striping material is deposited evenly onto said can seam area.

8. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which:

said slots are in the middle of the belt and are spaced equidistant from each other down the length of said belt.

9. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which:

said charging means comprises pins at a high voltage for generating corona discharge and located in the path of said projected striping material.

10. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 9 in which:

a vacuum source is mounted adjacent said charging means whereby the striping material which passes through said means is drawn into said vacuum source.

ll. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width comprising:

can feed means for feeding spaced can bodies past an application station;

an endless belt having slots spaced in series with their longitudinal axes along the direction of motion of said belt and traveling parallel to and in synchronism and phase with said can feed means whereby said can may be placed at said slot with its side seam toward said slot;

means for projecting powdered striping material in a direction generally parallel to the direction of motion of said can feed means comprising:

a tube of about one and one-half feet in length having a predetermined radius of curvature and making a smooth curve which lies in the same plane as the slots of said masking means;

means for electrostaticaliy charging said striping material;

and

means for charging said can to a different potential from said striping material whereby said charged striping material is attracted to said can to coat said can.

12. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 13 in which said tube has a minimum radius of curvature of three inches whereby the cross-sectional density of the powdered striping material taken across the tube is constant.

13. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 12 in which said projecting means further comprises:

an orifice having an elliptical shape with the major axis of the ellipse lying generally parallel to the surface of the can nearest to the orifice.

14. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 12 in which said projecting means further comprises:

a nozzle with an exit orifice having the shape of a rectangle with an outwardly curved section at the middle of each long side and the long axis of the rectangle is generally parallei to the surface of the can nearest to the nozzle.

15. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim ll comprising further:

a high-low vacuum apparatus for removing excess powder from the device when said powder does not deposit on said can side seam.

16. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 15 in which said high-low vacuum apparatus comprises:

a first pipe having a first end and, a second end, and

a port in said first pipe located downstream from said first end,

a vacuum source attached to said second end,

a second pipe having a first and a second end, the first end of said second pipe being attached to the port in the side of said first pipe to form a continuous conduit and the second end of said second pipe being open to the ambient air,

a valve located in said second pipe to allow ambient air to be drawn through said second pipe when said valve is in open position or to close off said ambient air when said valve is in closed position,

a motor connected to said valve for moving said valve from one position to another and having a first and a second electrical terminal,

an A.C. source having a first and a second terminal,

first conductive means connecting said first terminal of said AC. source to said first terminal of said motor,

can sensing means for detecting the presence of a can on the side striping device just upstream of the side striping station and having a first and a second terminal,

second conductive means connecting the first terminal of said sensing means to the second tenninal of said A.C. source, and

third conductive means connecting the second terminal of said can sensing means to the second terminal of the motor.

17. A can side striping device for coating the side seam of can bodies with a strip of predetermined width as set comprises: in claim 18 in which said third conductive means comprisers:

an electrical switch having a first and a second terminal,

fourth electrical conductive means connected between said first switch terminal and said second sensor terminal, and

fifth electrical conductive means connected between said second switch terminal and said second motor terminal.

18. A can side seam striping device for coating the side seam of can bodies with a strip of predetermined width as set forth in claim ll further comprising:

a mechanical variator having an input sprocket shaft and an output sprocket shaft,

a first rotary connecting means connecting said can feed means to the input shaft of said variator,

means for driving said endless belt,

a second rotary connecting means connecting said output of said variator to the endless belt driving means whereby the phase differences between said can feed means and said endless belt may be adjusted by adjustment of said variator.

19. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 15 comprising further:

can sensing means located above said endless belt just upstream of said powder projecting means for sensing the presence of a can, and

control means for turning said high-low vacuum apparatus to low vacuum when a can is near said can sensing means and to high vacuum when no can is near said can sensing means whereby all powder particles are aspirated into said vacuum apparatus.

20. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which said can feed means further comprises:

a plurality of rollers having said segmented belt disposed thereover,

an idler roller disposed between two rollers of said plurality of rollers,

biasing means attached to said idler roller to press said idler roller against said belt whereby belts of various lengths may be used to accommodate slot length and belt length to different series of cans having different lengths and requiring different belt lengths for each series of said cans. 

1. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width comprising: can feed means for feeding spaced can bodies past an application station; an endless belt having slots spaced in series with their longitudinal axeS along the direction of motion of said belt and traveling parallel to and in synchronism and phase with said can feed means whereby said can may be placed at said slot with its side seam toward said slot; means of projecting powdered striping material in a direction generally parallel to the direction of motion of said can feed means; means for electrostatically charging said striping material; and means for charging said can to a different potential from said striping material whereby said charged striping material is attracted to said can to coat said can.
 2. A can side striping device for coating the hot side seam of can bodies as set forth in claim 1 in which said endless belt comprises: a thin belt made of a non-wetting, high-melting point, flexible material.
 3. A can side striping device for coating the side seam of can bodies as set forth in claim 2 in which said thin belt is located very close to said can.
 4. A can side striping device for coating the side seam areas of can bodies as set forth in claim 1 comprising further: a vacuum source mounted adjacent said electrostatic charging means for cleaning the charging means; and a cleaning means mounted adjacent said endless belt for wiping striping material from said belt after it has passed said vacuum source.
 5. An apparatus for coating the side seam of a series of spaced cans comprising: can feed means for feeding spaced can bodies past an application station; a segmented endless belt disposed over rollers and having slots whose longitudinal axes extend in the direction of motion of said belt and of width and length such that a can may be placed upon said slot and the hot side seam fits snugly into said slot, means for projecting striping material in a direction generally parallel to the direction of motion of said can feed means, and into said slot area; means for electrically charging said striping material; and means for grounding said can whereby said striping material is attracted to said can.
 6. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which said projecting means comprises: a nozzle having a shaped exit orifice for control of the amount of striping material deposited at points on said can.
 7. An apparatus for coating the side seam of a series of cans as set forth in claim 6 in which: said shaped exit orifice has a cross-section with the outline of a rectangle whereby said powdered striping material is deposited evenly onto said can seam area.
 8. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which: said slots are in the middle of the belt and are spaced equidistant from each other down the length of said belt.
 9. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which: said charging means comprises pins at a high voltage for generating corona discharge and located in the path of said projected striping material.
 10. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 9 in which: a vacuum source is mounted adjacent said charging means whereby the striping material which passes through said means is drawn into said vacuum source.
 11. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width comprising: can feed means for feeding spaced can bodies past an application station; an endless belt having slots spaced in series with their longitudinal axes along the direction of motion of said belt and traveling parallel to and in synchronism and phase with said can feed means whereby said can may be placed at said slot with its side seam toward said slot; means for projecting powdered striping material in a direction generally parallel to the direction of motion of said can feed means comprising: a tube of about one and one-half feet in length having a predetermined radius of cUrvature and making a smooth curve which lies in the same plane as the slots of said masking means; means for electrostatically charging said striping material; and means for charging said can to a different potential from said striping material whereby said charged striping material is attracted to said can to coat said can.
 12. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 13 in which said tube has a minimum radius of curvature of three inches whereby the cross-sectional density of the powdered striping material taken across the tube is constant.
 13. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 12 in which said projecting means further comprises: an orifice having an elliptical shape with the major axis of the ellipse lying generally parallel to the surface of the can nearest to the orifice.
 14. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 12 in which said projecting means further comprises: a nozzle with an exit orifice having the shape of a rectangle with an outwardly curved section at the middle of each long side and the long axis of the rectangle is generally parallel to the surface of the can nearest to the nozzle.
 15. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 11 comprising further: a high-low vacuum apparatus for removing excess powder from the device when said powder does not deposit on said can side seam.
 16. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 15 in which said high-low vacuum apparatus comprises: a first pipe having a first end and, a second end, and a port in said first pipe located downstream from said first end, a vacuum source attached to said second end, a second pipe having a first and a second end, the first end of said second pipe being attached to the port in the side of said first pipe to form a continuous conduit and the second end of said second pipe being open to the ambient air, a valve located in said second pipe to allow ambient air to be drawn through said second pipe when said valve is in open position or to close off said ambient air when said valve is in closed position, a motor connected to said valve for moving said valve from one position to another and having a first and a second electrical terminal, an A.C. source having a first and a second terminal, first conductive means connecting said first terminal of said A.C. source to said first terminal of said motor, can sensing means for detecting the presence of a can on the side striping device just upstream of the side striping station and having a first and a second terminal, second conductive means connecting the first terminal of said sensing means to the second terminal of said A.C. source, and third conductive means connecting the second terminal of said can sensing means to the second terminal of the motor.
 17. A can side striping device for coating the side seam of can bodies with a strip of predetermined width as set forth in claim 18 in which said third conductive means comprises: an electrical switch having a first and a second terminal, fourth electrical conductive means connected between said first switch terminal and said second sensor terminal, and fifth electrical conductive means connected between said second switch terminal and said second motor terminal.
 18. A can side seam striping device for coating the side seam of can bodies with a strip of predetermined width as set forth in claim 11 further comprising: a mechanical variator having an input sprocket shaft and an output sprocket shaft, a first rotary connecting means connecting said can feed means to the input shaft of said variator, means for driving said endless belt, a second rotary connecting means connecting said output of said variator to the endless belt driving means whereby the phase differences between said can feed means and said endless belt may be adjusted by adjustment of said variator.
 19. A can side striping device for coating the side seam of can bodies with a stripe of predetermined width as set forth in claim 15 comprising further: can sensing means located above said endless belt just upstream of said powder projecting means for sensing the presence of a can, and control means for turning said high-low vacuum apparatus to low vacuum when a can is near said can sensing means and to high vacuum when no can is near said can sensing means whereby all powder particles are aspirated into said vacuum apparatus.
 20. An apparatus for coating the side seam of a series of spaced cans as set forth in claim 5 in which said can feed means further comprises: a plurality of rollers having said segmented belt disposed thereover, an idler roller disposed between two rollers of said plurality of rollers, biasing means attached to said idler roller to press said idler roller against said belt whereby belts of various lengths may be used to accommodate slot length and belt length to different series of cans having different lengths and requiring different belt lengths for each series of said cans. 